In a recent publication, Lee and colleagues, using data derived from the National Ambulatory Medical Care Survey and the National Hospital Ambulatory Medical Care Survey from the US National Center for Health Statistics, evaluated changes in osteoporosis therapy in women aged ≥ 40 years, during the period January 1997 to December 2005 [1]. These office-based physician and hospital ambulatory clinics data were analyzed for visits in which anti-osteoporosis medication was prescribed, provided or continued, before and after initial publication of the Women’s Health Initiative (WHI) results. These visits were estimated in 6-month intervals, the first 11 before the WHI and the last seven after the WHI publication. Results were extrapolated to a national estimate. Principal findings include that the overall prevalence of prescribing of anti-osteoporosis medication did not significantly differ before and after the WHI. However, the prescribing of estrogen decreased while that of bisphosphonates, calcium and vitamin D increased in both office-based physician and hospital-based clinic settings. The adjusted odds ratios and 95% confidence intervals for the likelihood of non-estrogen, anti-osteoporosis therapy (excluding calcium and vitamin D) after the WHI were 2.49 (2.04–3.04) and 2.42 (1.67–3.50), office-based and hospital-based, respectively, compared with 1.00 before the WHI. Additionally, visits by black women had a lower likelihood of being associated with non-estrogen therapy than other racial groups, although this difference was significantly different only in the hospital-based clinic group.

Comment

The study by Lee and colleagues, using both office- and hospital-clinic-based visit data provides an analysis of the prescribing of anti-osteoporosis therapy before and after the WHI. As the authors point out, based on their data, they are unable to address the question of anti-osteoporosis therapy use on an individual patient basis. In their study, it is not possible to determine whether a patient discontinuing one therapy is the same patient initiating another. Evaluating prescription data may provide additional insights compared to visit data when evaluating anti-osteoporosis therapy. Visit data may not be constant over time, for example it has been suggested that, following the publication of the WHI results, some women discontinued hormone therapy on their own and also discontinued seeing their physician. Hence, based on visit data alone, it may not be possible to conclude that the overall prevalence of osteoporosis therapy did not change post-WHI. It is possible that there was both a change in the overall prevalence of osteoporosis therapy as well as an increase in the use of non-estrogen therapy. It has been reported that there is a 35% lower rate of fracture among women taking estrogen than among women who have discontinued it [2]. In the US, comparing January to June 2003 with the same period in 2002, Prempro prescriptions declined by 66% and Premarin prescriptions by 33%. A study of women aged 40–69 years indicated that the incidence of fractures was greater post-WHI (2004–2005) than pre-WHI (2000–2001), following a decrease in hormone therapy use and ‘despite a concurrent increase in the use of bone-modifying drugs’ [3].